President Barack Obama announced Judge Merrick Garland as his nominee to replace deceased Justice Antonin Scalia on the Supreme Court, likely triggering a fierce battle with Senate Republicans who have vowed to block anyone from being appointed.

During a Rose Garden ceremony at the White House, Obama said his selection was extremely qualified for the position and that the Senate should take its responsibility to consider a nominee seriously.

Obama said that he chose Garland after an “exhaustive process,” calling the judge “one of America’s sharpest legal minds.”

Garland possesses honesty and integrity, as well as “respect and admiration from both sides of the aisle,” he added.

“This is the greatest honor of my life,” Garland said after the president finished speaking. “For me there could be no higher public service than serving as a member of the United States Supreme Court.”

Garland is considered a moderate liberal justice. The 63-year-old is the chief judge of the US Court of Appeals for the District of Columbia. Having served for nearly 20 years on the court, Garland was confirmed in a 76-23 vote back in 1997, earning the backing of 32 Republicans. He was also on the short list for the Supreme Court the last two times Obama appointed a nominee. In 2010, Senator Orrin Hatch (R-Utah) pushed Obama to nominate Garland instead of now-Justice Elena Kagan because “he would be very well supported by all sides.”

The president specifically referenced past bipartisan support for Garland, including Hatch’s comment that Garland is a “consensus candidate,” saying the judge’s name has come up “repeatedly” from Republicans and Democrats.

“To suggest that someone as qualified and respected as Merrick Garland doesn’t even deserve a hearing ... would be unprecedented,” Obama said.

At 63, Garland is the oldest nominee since President Richard Nixon nominated Justice Lewis Powell in 1971. He is two years older than Chief Justice John Roberts, marking a break from the trend of presidents nominating younger justices to ensure they remain on the court for decades.

Like Obama, Garland grew up in Chicago, Illinois and attended Harvard Law School, where he was a member of the Harvard Law Review. After graduating from law school, he worked as a clerk for Justice William Brennan, and worked at the multinational law firm Arnold and Porte. Garland was also a longtime prosecutor who helped the Justice Department oversee investigations into the 1995 Oklahoma City bombing.

Prior to the president’s announcement, reports from Reuters suggested that Obama’s final decision was between federal appeals judges Garland and Sri Srinivasan. In an email, Obama laid out his thinking on the selection process.

“In putting forward a nominee today, I am fulfilling my constitutional duty. I’m doing my job,” the president wrote. “I hope that our Senators will do their jobs, and move quickly to consider my nominee. That is what the Constitution dictates, and that’s what the American people expect and deserve from their leaders.”

Obama added that any nominee should possess an independent mind, unimpeachable credentials, and a mastery of the law. Secondly, the justice should understand the judiciary system’s limits, and that the Supreme Court’s job is not to make the law but rather to interpret it.

Finally, the president said any nominee must understand “that justice is not about abstract legal theory, nor some footnote in a dusty casebook,” and that they must grasp “the way it affects the daily reality of people’s lives in a big, complicated democracy, and in rapidly-changing times.”

Regardless of any nominee’s qualifications, the Supreme Court nomination process will likely be embroiled in a political battle considering 2016 is a presidential election year. Any appointment could dramatically alter the balance of the court, currently filled with four conservative and four liberal justices.

Ever since Scalia’s death in mid-February, which occurred with 11 months left in Obama’s second term, Republicans have promised to block any nominee from consideration, much less a confirmation vote. They have argued that Obama should not appoint a justice in the middle of an election year, and that the next president should be able to make the decision.

Democrats, including Obama, have countered that it is the president’s constitutional responsibility to nominate someone and that it is the Senate’s responsibility to consider them.

"It is tempting to make this confirmation process simply an extension of our divided politics… but to go down that path would be wrong, it would be a betrayal of our best traditions," he said. "I simply ask Republicans in the Senate to give him a fair hearing and a simple up-or-down vote."